AsIs {base} | R Documentation

## Inhibit Interpretation/Conversion of Objects

### Description

Change the class of an object to indicate that it should be treated “as is”.

### Usage

    I(x)

### Arguments

`x` | an object

### Details

Function `I` has two main uses.

- In function `data.frame`. Protecting an object by enclosing it in `I()` in a call to data.frame inhibits the conversion of character vectors to factors. `I` can also be used to protect objects which are to be added to a data frame, or converted to a data frame via `as.data.frame`.

  It achieves this by prepending the class `"AsIs"` to the object's classes. Class `"AsIs"` has a few of its own methods, including for `[`, `as.data.frame`, `print` and `format`.

- In function `formula`. There it is used to inhibit the interpretation of operators such as `"+"`, `"-"`, `"*"` and `"^"` as formula operators, so they are used as arithmetical operators. This is interpreted as a symbol by `terms.formula`.

### Value

A copy of the object with class `"AsIs"` prepended to the class(es).

### References

Chambers, J. M. (1992) Linear models. Chapter 4 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.

### See Also

`data.frame`, `formula`

[Package Contents]